BSC 2011 Lecture Notes - Lecture 3: Tracheid, Chloroplast, Plasmodesma
12 Sep 2016
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They had to: adapt to dry, high light (xeric) conditions, develop transport systems for water and nutrients, develop structural support, find new wats to disperse gametes and progeny. Cuticle: a waxy coating that slows water loss, layer that protects from rapid water loss. Stomata: closable openings that regulate gas exchange, get rid of oxygen produced, and allows carbon dioxide to enter, dispels extra water in the tissue, responds to certain stimuli. Pigments: protect against uv radiation, reflect or absorb uv light to use as energy to dispel. Spores: have thick walls containing sporopollenin, sporopollenin protects spores against drying out and decay, so resistant that they can stay round for thousands to millions of years, early spore fossils from 470 million years ago. Mycorrhizae: a mutually beneficial association with fungi, provides nutrients to plants from the soil in exchange for sugars. Sporophyte: diploid, dependent on the gametophyte for nutrition at some or all stages of development, usually remains attached.
